Sen. Claire McCaskill paid more than $15,000 for two other Senate Democrats and their wives to join her family in Cancun for a swanky winter vacation last year, according to recently filed financial disclosure forms.

The Missouri Democrat invited Sens. Charles Schumer, D-N.Y., and Jon Tester, D-Mont., and their respective spouses on the four-day trip to Mexico — paying for their airfare, hotel rooms and food, according to disclosure forms filed earlier this month by Schumer and Tester.

Schumer and his wife’s bill came to about $8,200, while the Tester family’s tab amounted to $7,400, the disclosure reports show. Schumer is now the Senate’s Democratic leader, and Tester served as chairman of the Senate Democrats’ campaign arm in the last election cycle. The high-powered Senate trio traveled to Cancun last February, although the reports do not specify where they stayed.

John LaBombard, a spokesman for McCaskill, said it was for a special occasion.

“This was a McCaskill family birthday celebration with family and personal friends, including colleagues, and the trip was publicly disclosed per Senate guidelines,” said LaBombard. He declined to say whose birthday they were marking, but McCaskill turned 63 last July, so the trip did not coincide with hers.

McCaskill is one of the wealthiest members of Congress, mostly through her husband’s investments. Joseph Shepard has a bevy of real-estate holdings, and the couple’s assets were worth between $19 million and $32 million in 2014, according to a tally by the Center for Responsive Politics, a nonpartisan government watchdog group.

The Senate Republican’s campaign arm immediately seized on the travel tidbit — first reported by Politico — calling McCaskill out for taking her “beach buddies” on a “lavish all-expenses-paid trip.” Republicans are hoping to unseat McCaskill in the 2018…